Climate Intervention in an Earth Systems Science Framework

Proceedings of a Workshop—in Brief

INTRODUCTION

Dramatic reductions in greenhouse gas emissions will be necessary to reduce the effects of climate change.¹ Current trajectories suggest that emissions reductions will fall short of the levels needed to avoid serious global warming impacts in this century.² Climate intervention or geoengineering techniques—strategies intended to cool the Earth or remove greenhouse gases from the atmosphere—are increasingly becoming technically feasible but remain controversial due to their transboundary nature, risks of unintended harmful impacts, and ethical concerns. Public engagement and ongoing collaboration across a wide spectrum of expertise will be important to understand how well climate interventions might work, their environmental and social impacts, and whether societies wish to accept them.

To consider how an Earth system science approach can inform research on climate intervention, The National Academies of Sciences, Engineering, and Medicine (National Academies) held a virtual workshop on June 20 and 22, 2023, titled “Climate Intervention in an Earth Systems Science Framework.” Opening remarks for the event were provided by Jim Hurrell (Colorado State University). He noted that the organizing committee brought together individuals with a wide range of physical, ecological, and social sciences expertise to explore climate interventions within the context of convergent³ research and the capacities of the National Science Foundation (NSF). The workshop drew on the National Academies report Next Generation Earth Systems Science at the National Science Foundation,⁴ which called upon NSF to pursue an Earth systems science initiative that emphasizes research on interconnections and feedback between natural and social processes; focuses on real-world problems; enhances the participation of social, engineering, and data scientists; and strengthens efforts to include diverse perspectives in research. In addition, Hurrell noted that the workshop drew on several other Academies activities, including studies on

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carbon dioxide (CO₂) removal and sequestration, solar radiation modification, and related areas.^5,6,7,8,9

This Proceedings of a Workshop—in Brief was prepared by rapporteurs as a factual summary of what occurred at the workshop. The statements made are those of the rapporteurs or individual workshop participants and do not necessarily represent the views of all workshop participants; the planning committee; or the National Academies of Sciences, Engineering, and Medicine.

EXAMPLES OF CROSS CUTTING ISSUES, NEEDS, AND OPPORTUNITIES

The workshop’s first session examined cross cutting issues and opportunities in climate intervention research to set the stage for in-depth discussions of particular climate intervention strategies and the role of NSF. In framing remarks, Manjana Milkoreit (University of Oslo) said that because climate intervention is a solution-oriented field, this research takes place in the context of ongoing political conversations and involves critical interactions with other proposed climate solutions. In addition, she noted that the idea of geoengineering has attracted significant controversy, necessitating important national and international conversations. “This research takes place in an unusual context of ongoing debates among scientists and governance actors, where there’s even disagreement of whether this research should take place, or what kinds of climate intervention research are legitimate, and whether it should receive public funding,” said Milkoreit. She also underscored the need to assess the different risks that come with interventions and compare those to the risks of climate change itself and the risks of other solutions while also examining how interventions fit into the new principles of next generation Earth systems science.

Human Dimensions of Climate Intervention

Holly Buck (University of Buffalo) provided a brief summary of climate intervention research investments over the past 15 years. She said that the 2010s saw increased interest in and funding for studying climate intervention, with a strong focus on interdisciplinary, assessment-focused research. During this time, NSF funding also followed the interdisciplinary, assessment-focused paradigm. These efforts demonstrated the need for convergence research, she said. Although interdisciplinary research is an important aspect of performing convergence research, Buck noted that investments in interdisciplinary research programs around climate intervention have declined in recent years. Looking ahead, she emphasized the need to analyze the social and environmental justice implications of climate intervention projects and technologies, examine land use implications and potential conflicts, build out roadmaps for energy and technology transitions in different countries, and attend to the intergovernmental and international dimensions of fossil fuel phaseout.

To enable informed decision-making around climate interventions, Jane Flegal (Stripe Climate) said that a critical role for research is to elucidate the trade-offs these technologies involve. These tradeoffs are not strictly about science and technical feasibility; they also involve economic, moral, aesthetic, and many other considerations. To shed light on these tradeoffs, climate intervention research is important, but is often of a different nature than other areas of research. It deals with open, complex, and unpredictable systems in which it is often impossible to isolate variables. It also encompasses systems with opaque goals that are often inherently political, value-laden, and hard to measure. These distinctions affect both how research is conducted and how people perceive the findings that it generates. Flegal remarked that an area with political disputes, like climate intervention, is not a natural fit for the traditional model of producing a greater quantity of science to decrease uncertainty and enable better decision-making. “Our knowledge about open system climate interventions will always be partial and uncertain. That does not mean we cannot or should not support research, but it does mean we have to grapple with those uncertainties in an explicit way.”

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Flegal emphasized the importance of embedding diverse parties in the design of climate interventions from the beginning. In particular, she noted that those conducting geoengineering research may not always understand the needs, conditions, constraints, and incentives facing policymakers who must make decisions about research funding allocations and the use of these technologies.

“This feels like an extraordinary moment, not just for climate intervention research, but for the scientific enterprise,” said Simon Nicholson (American University). “We have a chance here […] to do better than we have done in the past.” Nicholson emphasized that climate intervention requires technological process development but is inherently a social enterprise. It is, therefore, vital to recognize the governance questions that need to be asked and include a diversity of voices in addressing those questions. Building on this point, Christopher Trisos (University of Cape Town) stressed the importance of bringing the social dimensions together with the research and development aspects to consider what kinds of questions need to be answered and to ensure that the work moving forward is acceptable and responsible. “We talk about things like climate intervention as part of a pathway for protecting some of the most vulnerable people on the frontlines of the climate crisis,” he said. “I think in many contexts, we don’t actually know if that is true.”

Several speakers underscored how, for climate intervention, effective communication and public engagement are key. As a case illustration, Philip Macnaghten (Wageningen University) pointed to a U.K. experiment known as the SPICE (Stratospheric Particle Injection for Climate Engineering) Solar Radiation Management Project. For the project, researchers planned a field trial to spray water from a 1-kilometer-high hose attached to a hot air balloon over Cambridgeshire to see if this could have a cooling effect. The proposal brought up a number of social and political challenges which ultimately resulted in the project’s cancellation, demonstrating the strong influence of public perceptions, even for small climate intervention projects. Macnaghten said that the way public engagement happens is extremely important, especially in places with a strong contingent of climate skeptics. He added that stakeholder engagement that occurs on a global scale is challenging as well and would likely require various national funders working together through a collaborative research framework.

Juan Moreno-Cruz (University of Waterloo) made a case for developing a framework in which climate intervention technologies are examined as a bundle. “There are places where multiple techniques will be implemented together, but we don’t understand yet how these technologies will interact – on the science, social science, or natural science levels – or how they should be governed,” he said. He added that the potential for multiple countries to simultaneously pursue multiple interventions further complicates these considerations. Several panelists emphasized the importance of governance but noted that there are many unknowns surrounding how governance would work given the global nature of climate interventions. “We cannot expect individual researchers to set up entire governance regimes for every experiment they want to conduct,” said Flegal. Although some panelists expressed concern about governance posing undue barriers for research, Moreno-Cruz pointed out that successfully progressing through the mechanisms of governance can actually make it more likely that experiments will progress to implementation.

Physical Dimensions of Climate Intervention

In a panel focused on the physical dimensions of climate intervention, speakers continued to build on many of the social issues raised in the workshop’s opening session while delving deeper into the nuances of particular techniques and technologies. Keynote speaker Ken Caldeira (Stanford University) emphasized the importance of inclusion in climate intervention research. Since lower-resourced communities in the tropics will be hardest hit by climate change, he said, they need both capacity building and a voice in the discussion. “People I’ve spoken to from these countries have often expressed a view that climate change is something imposed on them by the rich north, and that, if there was a way that they could reduce the hazards of climate change safely, that they would want to consider it,” Caldeira said. He

noted that a recent report from the United Nations (UN) Environment Program emphasizes the need for a robust scientific review process by a global body such as the UN as well as a governance framework or frameworks that would pertain to small scale outdoor experiments and potential deployment.¹⁰

Caldeira also noted there are important differences in the characteristics and nature of various techniques. In particular, he said that carbon dioxide removal (CDR) approaches bear a greater resemblance to climate mitigation than to solar radiation modification, and he cautioned that lumping all interventions together under the rubric of geoengineering can lead to confusion. “A lot of the philanthropists and companies that are investing in CO₂ removal are doing so because they want to do social good or be seen as doing social good,” he said. “If what they’re doing gets tagged as geoengineering and is seen as controversial, that could negatively impact real projects that people are putting real money into.”

Reflecting on examples of priorities and the types of evidence that may be needed to address them, Michael Diamond (Florida State University) highlighted the need to distinguish between issues that are more empirical, such as mitigation or fossil fuel phaseout deterrence, and those that are fundamentally normative, such as different conceptions of respect for nature. He also drew a distinction between questions that require interdisciplinary work and those that may be best addressed within disciplines. Understanding how to achieve marine cloud brightening, for example, might be more discipline-specific, while questions around the local impacts of climate interventions, impacts on marine ecosystems, and the global or regional effects of changes in carbon circulation may be more interdisciplinary or transdisciplinary. He noted that NSF already has some effective initiatives for facilitating interdisciplinary work but said that he sees a lack of consistent support for such work that lasts from the initial team creation all the way through the research process.

Panelists also raised some considerations specific to particular climate intervention approaches. For solar radiation modification (SRM) with stratospheric aerosols, Ben Kravitz (Indiana University) said that interdisciplinary work and responsible governance will be critical and suggested that putting SRM field experiments under a federal umbrella could allow appropriate scrutiny of the environmental and social impacts and help to address many unanswered questions. Discussing the potential ecological impacts of climate intervention, Forrest Hoffmann (Oak Ridge National Laboratory) noted that although simulations have suggested that SRM might be a good candidate technique, few studies have investigated the potential impacts on ecological systems. Hoffman urged taking “a transdisciplinary approach... and new modeling paradigms to help us understand these complex interactions. Even beyond the social and geopolitical questions, we still have work to do on the physical, biological, and chemical side.”

Pete Smith (University of Aberdeen), spoke about nature-based CDR approaches, which, if implemented carefully, are good for biodiversity and people and also help with both climate change adaptation and mitigation. If all the natural climate solutions could be employed simultaneously, this would provide around 10 gigatons of CO₂ equivalent mitigation per year.¹¹ However, potential pitfalls include challenges in accounting for emissions mitigated, challenges in natural sinks’ storage capabilities, and potential disincentives to pursue emissions mitigation. Smith suggested that there needs to be more research into co-benefits and trade-offs of CDR, as the co-benefits could drive implementation of well-planned CDR.

Katherine Romanak (University of Texas at Austin) pointed out that carbon capture and storage projects are already being deployed as part of the Biden Administration’s infrastructure act.¹² However, she said that there is misinformed rhetoric due to the complexity of climate science, as well as the challenges

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in understanding the geological processes involved in storing and retaining CO₂ in the subsurface. “There are many carbon capture and storage projects moving into the Texas Gulf Coast, and what we see is communities that absolutely need to be brought into the process and absolutely need to be included,” she said. Findings from a social science study¹³ her team performed suggest that it can be helpful to focus outreach efforts on identifying community leaders who can understand the technology and then take that knowledge to their community.

Panelists also discussed the importance of modeling approaches that better reflect the complexity of the social factors involved in climate intervention and their interactions with the natural sciences. There has been some progress in this area by using integrated assessment concepts coupled with Earth system models. It was pointed out that models can be used to engage communities and decision makers, as well as people from different disciplines, although they can be misinterpreted, as well. In the context of SRM, for example, Kravitz said that models can be instrumental in informing what field experiments are needed but cautioned that modeling can also influence public perceptions and lead to confusion. “When we use a climate model as ‘climate in a box,’ regardless of how well our uncertainties are communicated, people focus on the conclusions as if the models are saying, ‘this is what will happen if we do SRM,’” he said.

SOLAR RADIATION MANAGEMENT

SRM encompasses several techniques intended to increase the reflectivity of the planet to achieve cooling or to sustain temperatures to counter climate change. Simone Tilmes (National Center for Atmospheric Research) provided framing remarks on this topic and Jim Haywood (University of Exeter) delivered a keynote address. Tilmes said that although various SRM approaches may have different levels of feasibility and effectiveness, SRM could potentially cool the climate more quickly than other types of climate interventions. Haywood said that SRM is being taken seriously by policymakers. For example, he noted that the World Meteorological Organization’s 2022 scientific assessment of ozone depletion included aerosol injection for the first time.¹⁴ In addition, the UN endorsed an independent expert review that highlighted the notion that SRM might offer the “last chance” to avoid extremely dangerous climate change impacts.¹⁵

Three main SRM strategies have been proposed: stratospheric aerosol injection (SAI), marine cloud brightening (MCB), and cirrus cloud thinning (CCT). Of these, SAI is the strategy that has been most widely modeled and discussed, Haywood said. This strategy mimics the well-documented cooling impact from volcanic eruptions, with most studies modeling the effects of injecting sulfur dioxide (the primary emission from volcanoes) into the stratosphere. If this aerosol is injected near the equator, the natural atmospheric circulation should spread it around the planet and increase reflectivity, although there remains significant uncertainty about the amount of cooling such injections would create. Models suggest that SAI, when employed in conjunction with emissions mitigation and CDR, could play a role in stabilizing global temperature or limiting the overshoot of temperature goals. Haywood noted that studies indicate that this approach could have a detrimental impact on the ozone layer,¹⁶ but it is unclear how significant this would be.

MCB is a strategy that would involve injecting particles – in particular, sea salt – into clouds above the ocean in an effort to increase their reflectivity. Haywood said that scientists are less confident that this would work as the limited evidence comes largely from studying clouds formed by moving ships. The complexities of this approach are difficult to model, in part because climate models typically have resolutions of hundreds

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of kilometers. Haruki Hirasawa (University of Victoria) noted that even at the smallest scales, there is still a question as to whether it is possible to deliver the correct size of sea salt aerosol to the atmosphere and whether, if the wrong size is injected, it might cause unintended darkening of clouds rather than brightening.¹⁷ Additionally, there is still limited understanding of how these aerosols interact with clouds and significant uncertainties in the representation of aerosol and cloud processes in climate models. Since cirrus clouds trap heat, CCT is based on the idea that thinning or removing cirrus clouds could help to cool the planet by letting more outgoing thermal radiation escape. However, Haywood noted that this is the least studied and the least understood SRM approach.

Wake Smith (Harvard University) said that although SAI seems to be more scientifically and technologically plausible than MCB and CCT, there is still work to be done. He pointed out that SAI is generally discussed as being deployed in the range of 20 kilometers above the surface, roughly double the cruising altitude of most airplanes. Although there is work focused on designing new planes or other delivery systems, it would likely take decades to ramp up to full implementation. “Stratospheric aerosol injection would have a rapid impact once we put the stuff in the sky, but not necessarily a rapid start,” Smith said.

Panelists discussed the role of modeling and other research approaches in advancing understanding of SRM strategies. Daniele Visioni (Cornell University) highlighted how multi-model approaches can help to reveal where models disagree, point to knowledge gaps and needed observations, and shed light on how interventions might play out at the regional scale. All of this can lead to improved climate models and increased confidence in modeling results. “We tend to imagine these modeling experiments as the end, when multi-model intercomparisons should be seen as the beginning,” said Visioni.

Karen Rosenlof (NOAA) said that although models can be used to look at the impacts on the surface, temperature, hydrologic cycle, ecosystems, and air quality measurements are needed to verify and validate the models that will be needed to examine global effects. Currently, NOAA’s Earth Radiation Budget Program is supporting efforts to take baseline measurements of the stratosphere unperturbed by stratospheric aerosol injection. She added that there is a need for monitoring capabilities as well as laboratory work to understand aerosols other than sulfate and that NSF could help fill these knowledge gaps with the development of instruments and platforms, and through additional support for measurement campaigns, lab work, and measurement networks.

Ines Camilloni (University of Buenos Aires) discussed perspectives from the Global South regarding SRM. She noted that although SAI could cool the planet quickly, to be effective in limiting global warming, it would need to be maintained for several decades or even centuries, with attendant risks that are not well elucidated. “An operational solar emission modification deployment will introduce new risks both to people and ecosystems, and these novel risks are poorly understood,” she said. Camilloni encouraged including researchers from the Global South from the outset to determine research approaches and priorities. Finding out how SRM would impact the Global South in particular involves data, tools, funding, communication, and capacity building in this part of the world. Camilloni said that more funding is needed for researchers in the developing world to study the potential impacts of SRM in their regions and suggested coordinating the regional assessment of potential benefits and risks across different sectors such as biodiversity, agriculture, hydrology, and human health.

Several panelists pointed out that there are important differences between the risks that come from a small deployment, a large-scale experiment, and full, long-term deployment of SRM approaches, and that improved understanding of the risks involved, at all of these scales, could be beneficial. In thinking about risks, many panelists also cautioned that it is key to compare the potential risks

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of climate interventions against the risks posed by the future climate trajectory rather than today’s climate.

LAND-BASED CO₂ REMOVAL AND SEQUESTRATION

Land-based interventions to remove and sequester carbon dioxide include, for example, reforestation, forest management, soil carbon management, bioenergy with carbon capture and storage, and direct air capture. Keynote speaker Peter Lawrence (National Center for Atmospheric Research) underscored the urgent need for such strategies to achieve negative carbon emissions given current emissions projections, which are insufficient to limit warming to 1.5°C.¹⁸ Both Lawrence and session chair Phoebe Zarnetske (Michigan State University) noted that some of the most effective ecosystems for land-based CDR, such as tropical forests, exist largely in developing nations, which also face the biggest barriers in implementing conservation strategies.¹⁹ To create an effective portfolio of CDR technologies, it is important to consider the costs and the benefits of placement, impacts on indigenous peoples and local communities, and ways to reduce non-target impacts, especially on biodiversity and ecosystem functions.

Although reforestation is a popular and well-researched strategy, Lawrence cautioned that it is not a cure-all. To assess CDR effectiveness, it is important to consider the permanence of carbon storage, which depends on the pathway by which carbon is captured from the atmosphere, the process by which it is converted either through crops or tree biomass, and then how it is maintained in the soil. Lawrence pointed out that biofuel crops could be more effective at carbon removal than reforestation in some situations, but he noted that in either case, the carbon sinks grow smaller as the atmospheric CO₂ concentration grows larger because these living systems will themselves be affected by the changing climate.

Bruno Basso (Michigan State University) discussed opportunities to reduce the carbon that agricultural systems currently emit, such as through the use of cover crops and no-tillage systems that protect soil, reduce fertilizer use, enhance soil carbon sequestration, and facilitate carbon removal. Toward this end, the U.S. Department of Agriculture is investing about $3 billion to facilitate the adoption of cover crops, and Basso said farmers are keen to obtain these incentives. In addition, some farmers have created a revenue stream by selling carbon offsets for carbon sequestered in the soil for as high as $75 per ton sequestered. Basso noted that digital technologies can help to further increase the efficiency of resource use in agriculture, for example, by helping farmers to identify low productivity areas within fields, which could be converted for biofuels or CDR.

Projections indicate that a wide range of emissions pathways could help to achieve international targets for limiting global warming. However, the scale of deployment for interventions used in these scenarios remains far from the deployments happening in reality. To help close the gap, Sabine Fuss (Humboldt-Universität zu Berlin) stressed the need to pursue a diversified CDR portfolio. In combining conventional and emerging CDR strategies, she said it is important to think about which approaches would work best in what locations and account for feedback effects, disturbances, and differences in permanence. Recognizing the multifaceted nature of the issue, Gyami Shrestha (Lynker Corporation) said that carbon removal strategies must span across sectors and ecosystems; scale along the terrestrial, coastal, ocean, atmospheric, and societal interfaces; and be co-produced and implemented with local communities in a way that is equitable and respectful.

Stephanie Roe (World Wildlife Fund) noted that many countries and companies have committed to addressing multiple global challenges and are looking for integrated pathways to meet their goals. To accomplish this, she suggested that CDR interventions should be designed with multiple core benefits from the beginning by including relevant constraints and thinking about what types of actions might deliver multiple outcomes. Including ecosystem types, key biodiversity areas, and ecosystem services will likely involve new models that

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can incorporate different ecosystem types with high spatial resolution and allow for distinguishing subtypes, such as a primary forest versus managed forest. In assessing which strategies to employ where, she said it is also important to incorporate natural capital accounting, a method which considers not only the cost of implementing an intervention but also the cost of doing it wrong.

Building on these points, Shrestha said that scientists and investors are becoming more focused on the scientific basis for carbon monitoring, reporting, and verification (MRV) to guide effective and efficient CDR strategies. She suggested that NSF could help support this by facilitating the sustained development of strategies, technologies, and partnerships for MRV of carbon removal across all Earth system components and sectors. The agency could also help formulate improved governance strategies for carbon removal and help advance understanding of how different Earth system components could react to different climate interventions, she added.

Panelists suggested several potential impediments to scaling up CDR, including an inadequate understanding of technological limitations, especially over long timelines; limited representation of disturbance or succession in modeling carbon cycling in ecosystems; gaps in understanding the cumulative impacts of climate change and how changing fire regimes may impact forests and ecosystems; and a dearth of data and research funding in the tropics. Some panelists also suggested developing the governance and policy to support CDR, including mechanisms to provide incentives so that landowners, farmers, and foresters can implement these solutions in a way that delivers on multiple outcomes.

OCEAN-BASED CO₂ REMOVAL AND SEQUESTRATION

Joellen Russell (University of Arizona) introduced the session on ocean-based CDR and sequestration, an area that includes several different approaches, each with critical considerations around both technological development and governance. Margaret Leinen (University of California, San Diego) provided an overview of several proposed techniques. For example, adding iron to the ocean could boost photosynthesis and thereby enhance phytoplankton growth to increase CO₂ uptake, while adding alkaline substances could enhance the ocean’s natural carbon sink. Other approaches involve enhancing natural ocean processes without adding any materials. One example is artificial upwelling, in which nutrient-rich water is moved from depths of about 100 to 200 meters up to the surface to boost phytoplankton growth. Growing algae or restoring marine ecosystems such as seagrass and mangroves could also help to capture more CO₂. Finally, some have proposed using electrochemical processes to extract CO₂ from seawater and then storing it either in the deep sea or on land.

Overall, Leinen said that the effectiveness of sequestering CO₂—and how that sequestration could be measured and assessed—is largely unknown for most proposed ocean-based CDR techniques. Additionally, there is a dearth of knowledge on the locations suitable for performing these types of interventions and on how they might impact ecosystems if deployed at scale. In order to guide informed decisions about experiments with and eventual full-scale deployment of such techniques, she said that ethical and transparent research efforts are needed to understand whether and how it makes sense to pursue marine CDR. She suggested that NSF could help set standards for research in this area to inform principles and regulations, which could include ethical considerations; requirements for MRV; and guidance for sequential scaling.

Several participants noted that, for efforts to combat climate change, time is of the essence. Matthew Long (National Center for Atmospheric Research) said that the ocean sink would need to be doubled by 2050 to keep warming below 2°C, underscoring the urgency of orienting research toward action. “To enable this industry to scale, we have to move fast, and we have to set the trajectory appropriately so that science is at the forefront of leading this initiative,” he said. Phillip Boyd (University of Tasmania) said that to speed research, it will be helpful to learn from the existing knowledge base; use natural analogs such as the Black Sea, where geochemical weathering is carrying out ocean alkalinity enhancement; and build experimental capacity. “The

next 10 years is crucial,” he stressed. “The time for capacity building is short, and right now there is very little experimental capacity.”

Panelists discussed several key research questions in advancing understanding of marine CDR. Long emphasized substantial challenges involved in quantifying ocean CDR due to complicated baselines, slow CO₂ equilibration, large spatiotemporal scales, and unknowns of how ecosystems will respond. He also commented on a need to adapt models and tools developed in the Earth system modeling community toward bespoke systems for ocean verification since current models are not fit for this. John Dunne (NOAA) noted that the logistics involved in tracking purposeful changes to the ocean carbon cycle will be daunting and will require globally consistent tracer release protocols across direct CO₂ injection, alkalinization, and iron fertilization. He said that marine CDR solutions that leverage ecological enhancement; restore productivity, biomass, wetlands, and seagrasses; and reduce eutrophication should be prioritized.

Building on these points, Sarah Cooley (Ocean Conservancy) said that a highly coordinated body of publicly supported, multi-disciplinary research is necessary to understand all the possible ocean-based CDR approaches. “It’s becoming really clear that how we do the research is just as important as what we research,” she said. She added that there is much to be learned from other non-marine areas of technology development in terms of implementing iterative rounds of development, testing, and scaling and consultation.

Cautioning against rushed, opaque, highly privatized research that champions specific CDR approaches, Cooley urged a focus on inclusive, place-conscious research that is transparent and vets CDR approaches for their outcomes regarding the environment, the economy, carbon cycle, society, and governance. “NSF can help research outcomes be more equitable by ensuring that multiple ways of knowing are incorporated into this research, that the broadest possible array of disciplines are included, and that effective knowledge transfer happens among expert areas,” she said. Dunne further emphasized the need for engagement, transparency, inclusiveness, and deliberative and robust science, positing that there is a critical need for more oceanographers who are not only fluent in the science but who also embrace the societal, political, and legal contexts to enable a solutions-oriented corporate and non-governmental organization workforce.

Romany Webb (Columbia University) discussed the fact that legal considerations may have significant bearing on whether, when, where, and how research into ocean CDR is performed and scaled up for deployment. “There is a recognition that we need more research—that we don’t yet have the information we need to fully assess these techniques and make decisions about their deployment—but, on the other hand, we’re seeing all this corporate activity that is premised on the assumption that these things work and can be deployed at scale,” Webb noted. She said that effective governance is critical to ensure that ocean CDR research happens in a safe and responsible way that maximizes benefits and minimizes risks to the environment and communities but cautioned that existing legal frameworks are not particularly well-suited to do this. Although many U.S. laws may affect CDR projects, they do not address these activities directly and many impose duplicative and sometimes even conflicting requirements that could hamper certain research projects. Legal confusion and gaps might also create opportunities for rogue actors to move forward with testing marine CDR strategies without appropriate safeguards in place. To address these risks, Webb called for greater coordination and collaboration between government agencies to ensure effective regulation of marine CDR activities and suggested that NSF could help with filling some of the gaps in the legal framework and supporting system compliance.

Reiterating the importance of expanding the study and development of ocean-based CDR methods, several panelists expressed concern about the fragmentation within existing governance frameworks. Cooley suggested that NSF could play a role in brokering connections between experts and policymakers to help

achieve a shared understanding of responsible research practices in this area.

While publicly funded efforts are helpful toward ensuring an equitable and just approach to ocean governance and ocean management, Long added that the framework for public investment also needs to consider the research and infrastructure necessary to underpin a large new economic sector and how to create opportunities for empowering the private sector. This may involve leveraging action-oriented work while ensuring that science stays at the forefront.

THE ROLE OF THE NATIONAL SCIENCE FOUNDATION

In the workshop’s final session, participants built upon the opportunities, concerns, and strategies discussed in previous sessions with a focus on NSF’s role in addressing climate intervention research needs. Sonali McDermid (New York University) introduced the session, challenging participants to consider insights from the workshop discussions with an eye toward forward-looking goals. She asked participants to consider whether climate intervention proposals could explicitly include ethical considerations, how governance could be featured in supported work, and how to facilitate inclusion and funding of diverse partners, particularly those outside the United States.

Lynn Badia and John Volckens (Colorado State University) delivered a joint keynote presentation on the role of transdisciplinary science in advancing climate interventions research. “The work of climate intervention is equally a scientific and social enterprise,” said Badia. She and Volkens posited that the research complexities, uncertainties, and risks involved in climate interventions point to key roles for the social sciences and humanities and also call for new structures that enable various disciplinary experts to co-create research questions and trajectories together. They also described their vision to create Advanced Research Projects Agency–Climate (ARPA-C), a transdisciplinary initiative involving public-private partnerships and social science and systems to spur progress in researching climate interventions.²⁰

The presenters said that transdisciplinary work is important to understand the complex externalities involved in climate interventions, to ensure equity and justice in their study and deployment, to prioritize human well-being rather than focusing solely on technology, and to leverage human-centered pathways. However, they highlighted their own experiences to illustrate the fact that building transdisciplinary expertise involves years of training for individuals and that building functional interdisciplinary teams relies on adequate funding and years of effort.

Several panelists offered perspectives on NSF’s role. James Arnott (Aspen Global Change Institute) posited that there is a fundamental misalignment between the action-oriented science framework required for climate intervention research and the traditional discovery-focused orientation of NSF. To incorporate justice and equity and facilitate transdisciplinary collaboration across science, policy, and practice may require the public science enterprise to shift into a more problem-solving mode and a more proactive mode of program management, he suggested.

Bill Easterling (Pennsylvania State University) highlighted some strengths and weaknesses of NSF’s strategies and structures in the context of climate intervention. One of NSF’s core strengths, he said, is advancing convergence science approaches and a more systems-based understanding of nature, the world, and people, including how they interact with the world and how they view the climate problem. However, he also noted that NSF remains a siloed organization and there are many untapped opportunities to draw upon different disciplines and facilities.

Robert Kopp (Rutgers University), who leads an NSF-funded hub²¹ often seen as a model of transdisciplinary research in Earth system science, said that it is key to elevate the investment in ethics and governance and for

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social science studies to be core elements and drivers of projects. While recognizing the value of actionable science, he argued that NSF should remain focused on the broad health of the U.S. scientific enterprise and not attempt to fully transition into an applied technology program like some programs administered by the U.S. Department of Energy. He also said that convergence research programs are critical but noted that this does not necessarily mean that every project within such programs must be convergent. To advance responsible climate intervention research, he suggested creating a new four-part strategy comprising programs on global climate risk management (to characterize interventions and their trade-offs across scales and values); innovative solutions to climate change (to examine the scientific, technical, socioeconomic, and ethical feasibility and acceptability of specific technical solutions); global centers for climate intervention assessment, ethics and governance (to focus on the ethical dimensions of climate intervention and related research); and climate intervention research coordination networks that link the other three programs together.

Several panelists commented on the roles and interactions between different disciplines and fields in informing how climate intervention research proceeds. Benjamin Sovacool (Boston University) highlighted the value of social sciences and the arts and humanities in understanding and explaining the risks surrounding climate change and climate interventions. For instance, he said that arts and humanities disciplines can help inform how risks across all the different systems involved in research are depicted, defined, and communicated, while the social sciences can shed light on how these risks are interpreted and deconstructed as well as how policies are made to plan for them. Sovacool underscored the need for these disciplines, along with many disciplines across science and engineering, to work together to contribute to climate research in a more holistic way.

Michael Oppenheimer (Princeton University) emphasized the urgent need for a national — and eventually global — framework for governing experimentation with SRM. The lessons learned in such a process would be useful for grappling with international governance, including the issue of whether to let SRM proceed at all, and he added that such a framework might also be applicable to CDR in some respects. He suggested that NSF could identify, catalyze, and support development of the complex knowledge system needed to establish an appropriate level of governance, a process that he said would require a coherent knowledge base grounded in natural science, social science, and the many disciplines that deal with culture, values, and ethics.

Some panelists suggested that NSF could do more to encourage international participation and collaboration in the field of climate intervention by developing new mechanisms for promoting cooperation with partnering agencies across the world, in addition to other federal agencies. Recognizing the challenges inherent in coordinating research investments and governance, several panelists suggested that global centers could be helpful and pointed to the Joint Programming Initiative²² in Europe as an example of effective international collaboration.

Many panelists reiterated the critical role of convergence research in addressing climate change. Some suggested that the time is right for academic institutions to provide incentives that support convergent research. For example, this could include finding new ways to account for publicly engaged work in terms of promotion and tenure, and making changes that allow for the time necessary to form functioning interdisciplinary or transdisciplinary teams. The academic community could develop guidelines that funders would enforce by investing their money in universities that demonstrate a commitment to ensuring that conducting transdisciplinary work is a pathway to a sustainable career. Panelists also pointed out that NSF’s new Directorate for Technology, Innovation, and Partnerships could help support broader engagement toward this end.

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Lili Xia (Rutgers University), Margo Corum (National Academies), and Brent Heard (National Academies), offered closing reflections. As several speakers pointed out, one useful way of thinking about the current challenges surrounding climate intervention is to envision ourselves 20 years into the future and consider what information we might wish we had gathered now, Xia said. She noted that investing in climate intervention research is not necessarily about selecting solutions, but instead gathering information that is useful to assess options and make informed decisions. Corum noted that there is clearly an appetite for working across disciplines and addressing environmental justice and ethical considerations, as expressed by multiple workshop participants. Heard tied the themes that arose during the workshop back to the characteristics of an integrated Earth systems science approach called for in the Next Generation Earth System Science at the National Science Foundation report. He noted the report’s call for facilitating convergence of social, natural, computational, and engineering sciences to advance science and inform solutions to earth systems; for ensuring diverse, inclusive, equitable, and just approaches; and for the need to educate and support an effective Earth system science workforce. The integrated research characteristics of prioritizing engagement and partnerships with diverse stakeholders and of using observational, computational, and modeling capabilities synergistically to accelerate discovery and convergence were also themes raised during the workshop. “It’s not just about the techniques,” Xia said. “We need to understand whether the techniques work and how we’re going to scale up, but also, we need to have the right monitoring system and feedback system to understand the impact on society, ecosystems, [and] human health, and we need to think about the international governance and how [to] coordinate with different nations and address the [shared] issue we’re facing.”

DISCLAIMER This Proceedings of a Workshop—in Brief was prepared by Margo Corum, Anne Johnson, Brent Heard, and Nancy D. Lamontagne as a factual summary of what occurred at the workshop. The statements made are those of the rapporteur(s) or individual workshop participants and do not necessarily represent the views of all workshop participants; the planning committee; or the National Academies of Sciences, Engineering, and Medicine.

COMMITTEE MEMBERS James W. Hurrell (Chair), Colorado State University; Christopher B. Field, Stanford Woods Institute for the Environment; Sonali Shukla McDermid, New York University; Majana Milkoreit, University of Oslo; Joellen L. Russell, University of Arizona; Simone Tilmes, National Center for Atmospheric Research; Lili Xia, Rutgers University; Phoebe Zarnetske, Michigan State University.

STAFF Margo D. Corum, Brent Heard, Emily Bermudez, Sabah Rana (through May 2023). Deborah Glickson, Board Director

REVIEWERS To ensure that it meets institutional standards for quality and objectivity, this Proceedings of a Workshop—in Brief was reviewed by James W. Hurrell, Colorado State University, and Samantha Koretsky, National Academies of Sciences, Engineering, and Medicine. Lauren Everett, National Academies of Sciences, Engineering, and Medicine, served as the review coordinator.

SPONSORS This workshop was supported by the National Science Foundation.

SUGGESTED CITATION National Academies of Sciences, Engineering, and Medicine. 2024. Climate Intervention in an Earth Systems Science Framework: Proceedings of a Workshop—in Brief. Washington, DC: The National Academies Press: https://doi.org/10.17226/27476.